Process of sintering ores.



A. H. RICHARDS. PROCESS OF SINTERING ORES. APPLICATION 'FILED oqnn. 1915. RENEWED MAY 10.1918.

1,292,059, Patented Jan. 21,1919.

Fig.1-

in the UNITED sTATEs PATENT canton.

ADELBERT H. RICHARDS, OFSALT LAK SMELTING & REFINING (30., A

E CITY, UTAH, ASSIGNOR 1'0 AJtIERICAN CORIORATION' OF NEW J ERSEY rnocnss or smme onus.

, more perfectly sintered product than is produced by present methods.

Ores are sintered and roasted at present by igniting the top layer of a charge and supporting the combustion by drawing air down through the charge until-the zone of combustion has reached the bottom of the layer. This is usually accomplished by dc positing a layer of the ore 'to be treated on an endless belt of traveling grates, which carry the layer of ore under an ignition flame and over one or more vacuum boxes. Ores so treated have been found on analysis to contain some sulfur and other combustible products showing that the sintering and roasting is not complete and efforts to re ignite the charge to burn out the products charge is raw now used have a uni have not, so far, proven successful.

- It is noted that as the zone of combustion is drawn down-through the charge the burnt portion of the layer becomes somewhat porous which allows a larger amount of air tojpass through the layer than when the or unsinteredj There is thus produced a tendency toward drawing a greater amount-of air through the partly nished' charge than is drawn through the freshlyignited char e.- As themachines orm vacuumfunder all portions of the charge, it is obvious that these sintering machines arenot workin at their maximum eiliciency along all portions of their length.

Endeavors have been 'made to remedy this i condition by providing diiferent vacuums in the several wind partially successful but different boxes and this has been charges and even different portions of the same" .vary in their combustible constituents so that it is difficult to so regulate the intensities of the several vacuums to produce just the proper degrees of roasting and sin tering under all conditions., A

Specification of Letters Patent. 7 Application flied October 27, 1915, Serial No. 58,111.

, each layer which this is satis actorily Patented Jan. 21, I919. Renewed May 10, 1918. Serial No. 233,789.

Accordingly an object of my invention is to obtain a well roasted and sintered product independent, or substantially independent, of the character of the ore under treatment.

Another object of my invention is to increase the capacity of known types of sintering machines by utilizin draft creating portions thereof, which, unc are assisting 'but little the ores.

One means by which these objects may be in the sintering of ,attained without seriously modifying the present types of sintering machines is to deposit a charge of the ore 'on the traveling grates of the present machine, ignite the same and subjecting the ignited mass to the action of a current of air directed downwardly therethrough, as is usual with known sintering processes. Before the charge has been completely sintered, however a second charge'in the form of a layer of less depth than the preceded layer is deposited on the top of the first layer and ignited. Both layers are then sub ected to t e action of a downwardly directed currentof air passing therethrough and for this purpose the succeeding vacuum boxes now present in these machines may beutilized. Another layer may be imposed upon the preceding lower layer and in fact, any number of la ers may be superimposed upon each other. Iowever, the number of layers and the thickness of goes to make up the charge that can be treated at the least cost per unit of mass depends upon the capacity of the machine and the character of ore under treatment.

or present methods,

The best sinteringh'esults are obtained apparently b aslow burning process and -initial portion of the operation. The grad- 9 obtained during the o ually increasing portions of-.the burnt out charge, however, permit of a rapid increase in the amount of air supplied to the burning zone of the charge and accordingly accelerates the operation. The addition of the fresh char e may be timed to intercept this accelerated action at a point where the action is about to progress too rapidly but it is within the scope of this invention to deepen the charges progressively at the rate of move ment of the combustion zone through the p This process has been carried out with ad- 45 imposed charge.

vantage by means of a sintering machine of the conveyer type, suchas is illustrated in the accompanying drawings in which:

@The figure 1s a side elevation of a modified 5-"fo of Dwight and Lloyd sintering ma loiiger than the conventional type of such machines and thus provide for a large tonnage over any machine now known with a resulting decrease in cost per ton of roastin With any present size smtering mach ne a larger tonnage is realized due to the 1 creased number of layers which aresint ng at a given time. In this machine a A frame 2 supports an endless chain of grates 3 passing about and actuated by some suitable driving means, such as a sprocket wheel 4. A feed hopper 5 is positioned to direct a continuous stream of the ore to be treated onto the upper line of grates and to spread the same evenly in a layer of uniform thickness. ,The most satisfactory working thickness of this layer is dependent obviously upon the capacity of the machine, the rate of travel of thegrates and the character of the ore under treatment, but in general, work- 36 ing with a layer of from four to six inches in depth has given the most satisfactory repsults.

- An igniting device preferably in the form 0 a mufiier 6 is disposed above the layer in position to ignite the upper surface of the spread layer. The ignited layer is passed over one or more vacuum or wind boxes 7 designed to cause a draft to pass through the layer.

40 gi spharge hopper 8 and cooperating igniting l downwardly directed e ice 9 are positioned beyond the hopper 5 and spaced therefrom a distance dependent upon the" point in the travel of the grates at which it is described to introduce the super- The particular location of tl iis second hopper depends, among other factors upon the rate of travel of the grates, upon the rate of travel of the combustion zone through the ore and upon the point at.

"Which it is desired to retard the acceleration 1 of the rate of travelof the combustion zone through the charge. In its practical operation it has been found desirable to so, design this second hopper that a smaller amount of ore is fed than Was deposited by the preceding hopper and a layer of about one inch in depth has given the most perfectly sintered resulting product.

"It is understood that any number of these discharge hoppers and coacting igniting devices may be disposed along the travel of the ore and very satisfactory results have been obtai ed by disposing a lurality' of wind boxe along the length 0 the machine and carrying the vacuhm therein higher as each A second.

additional charge is added. This vacuum is regulated by suitable controlling dampers which are adjusted whenever necessary to insure the proper treatment of the ores passing through the machine.-

By means of a device of this character two or more separate layers ,are roasting and sintering at the same time so that a crosssoction of the charge would show layers of burning zones separated by layers of porous roasted sinter. This not only provides for an increase in capacity of the machine but results in an improvement in the resulting product.

The new layers of charge gradually sinter and fuse into the lower layers so as to form a solid porous product with no distinctive dividing line between the layers and uni formly sintered throughout the mass.

At the same time high'vacuums are maintained in the wind boxes and this high vac- While the rate of travel of uum is utilized. the combustion zone through the material is reduced over the former methods still the fact. that there are several zones burning simultaneously permits the grates to travel at the old speed and thus insures as rapid a roasting and sintering as was possible with the single layer machines.

Further this multiple layer process is valuable in that the finished; product is more thoroughly sintered than by the one. layer process, and is produced at a lesser cost per ton of charge roasted.

Having thus described my invention, I claim:

1. In the art of sintering .metalliferous ores, the process which consists in subjecting an ignited charge of ore to the action of a downwardly directed current of air passed through the charge, said charge oflfering a res stance to the passage of the air which resistance gradually decreases as the charge is sintered, adding a fresh charge of ore to the top of the next adjacent lower burning charge when the air resistance through this lower charge has reached a desired value, igniting said fresh charge and subjecting both charges to the action of a current of downwardly directed air passed therethrough.

2. In the art of sintering metalliferous ore, the processwhich consists in causing a layer-of ignited ore to travel in one direction, subjecting said layer to the action of a downwardly directed current of air passed ther'ethrough, depositing a second layer on top of said first named layer after the same I? ores, the

has been subjected to the action of said air current for a definite time, igniting said second layer and causin both layers to be subjected to the action 0 a downwardly directed current of air passed therethrough.

In the art of sintering metalliferous ores, the process which consists in subjecting a layer 0 ignited ore to the action of a current of air passed therethrough, and gradually increasing the depth of said layer thereby to cause the air supplied to any portion thereof to become less active as this portion approaches its completely sintered state.

4. In the art of sintering metalliferous ores, the process which consists in subjecting a burning layer of the ore to the action of an air-current passed therethrough to sinter the same, replenishing said ore with fresh quantities thereof during the progress of the sintering action and igniting said added ore.

5. In the art of sintering metalliferous process which consists in successively adding layer after layer of ore upon each preceding layer, separately igniting each layer as deposited and simultaneously subjecting all layers to the action of a current of air passed thercthrough.

6. In the art of treating metalliferous ores, the process which consists in causing. a current of air to pass through a layer 0 ignited ore to support the combustion necessary to sinter t e ore and increasing the depth of said layer as portions of the same ap roach their completely sintered state.

. In the art of sintering a layer of metallayer thereby progressively subjecting the layer to the actions of successively less active bodies of air as the layer of unsintered ore is decreased.

8. In the art of sintering ore, which consists in formin a layer of ore, igniting the top surface 0 said ore, causin a draft to pass downwardly through sai layer to carry a burning zone gradually through the layer and depositing a second layer of ore on said first layer when the burning zone has penetrated the first layer for a definite distance.

the process Signed at Salt Lake City, in the county of Salt Lake and State of Utah, this 7th day of October, A. D. 1915.

ADELBERT H. RICHARDS. 

